Systems and methods for preventing high-radiant-flux light, such as laser light or a nuclear flash, from causing harm to imaging devices, such as a camera or telescope. In response to detection of high-radiant-flux light, the proposed systems have the feature in common that a shutter is closed sufficiently fast that light from the source will be blocked from reaching the image sensor of the imaging device. Some of the proposed systems include a folded optical path to increase the allowable reaction time to close the shutter.

A LIDAR system includes a light source configured to output light. A portion of the light is included in a LIDAR signal that travels a LIDAR path from the light source to an object located outside of the LIDAR system and from the object to a filter and from the filter to a processing unit. The processing unit is configured to convert optical signals that include the LIDAR signal to electrical signals. A portion of the light is also included in one or more misdirected signals. Each of the misdirected signals travels a different misdirected path from the light source to the filter. Each of the misdirected paths is a different path from the LIDAR path. The system also includes a filter being configured to filter out the LIDAR signal from the misdirected signals. The system also includes electronics that generate LIDAR data from the electrical signals.

A LIDAR system includes a light source configured to output light. A portion of the light is included in a LIDAR signal that travels a LIDAR path from the light source to an object located outside of the LIDAR system and from the object to a filter and from the filter to a processing unit. The processing unit is configured to convert optical signals that include the LIDAR signal to electrical signals. A portion of the light is also included in one or more misdirected signals. Each of the misdirected signals travels a different misdirected path from the light source to the filter. Each of the misdirected paths is a different path from the LIDAR path. The system also includes a filter being configured to filter out the LIDAR signal from the misdirected signals. The system also includes electronics that generate LIDAR data from the electrical signals.

A counter measure apparatus and method for modifying a path of an electromagnetic detector signal (204) so as to prevent incidence thereof on a platform (200), the apparatus comprising an electromagnetic radiation source, communicably coupled to a control system. The control system is configured to create an atmospheric element (202) operative to simulate a physical electromagnetic radiation path modifying device within an atmospheric volume located in said electromagnetic detector signal path (204) by causing electromagnetic radiation from the source to be applied to a selected plurality of three-dimensional portions of said atmospheric volume so as to heat and/or ionise the air within said portions, wherein said selected portions are spatially located together in a substantially unbroken, three-dimensional configuration.

A counter measure apparatus and method for modifying a path of an electromagnetic detector signal (204) so as to prevent incidence thereof on a platform (200), the apparatus comprising an electromagnetic radiation source, communicably coupled to a control system. The control system is configured to create an atmospheric element (202) operative to simulate a physical electromagnetic radiation path modifying device within an atmospheric volume located in said electromagnetic detector signal path (204) by causing electromagnetic radiation from the source to be applied to a selected plurality of three-dimensional portions of said atmospheric volume so as to heat and/or ionise the air within said portions, wherein said selected portions are spatially located together in a substantially unbroken, three-dimensional configuration.

A first device may emit a first modulated signal within an environment that includes a second device that is located close in proximity to an object. The second device may capture the first modulated signal and determine a second modulated signal having a phase that is different from that of the first modulated signal. In response to capturing the second modulated signal, the first device may determine a phase difference corresponding to the first modulated signal and the second modulated signal using time-of-flight (TOF). Using the phase difference, the first device may determine the distance between the first device and the object. In embodiments where the phase difference is zero, the first device may be unable to detect the presence of the object.

In an electromagnetic cloaking structure, a refractive index distribution has a high refractive index region which is provided around a shielding space and has a maximum value in a plane surrounding the shielding space and in which a refractive index decreases gradually from the centroid of the shielding space along a radial line passing through the plane so as to be close to an average refractive index and a low refractive index region which has a minimum value at two points having the shielding space and the high refractive index region interposed therebetween on a virtual optical axis passing through the shielding space and in which the refractive index increases gradually from the two points in a direction opposite to the high refractive index region on the virtual optical axes, on which the two points are placed, so as to be close to the average refractive index.

In an electromagnetic cloaking structure, a refractive index distribution has a high refractive index region which is provided around a shielding space and has a maximum value in a plane surrounding the shielding space and in which a refractive index decreases gradually from the centroid of the shielding space along a radial line passing through the plane so as to be close to an average refractive index and a low refractive index region which has a minimum value at two points having the shielding space and the high refractive index region interposed therebetween on a virtual optical axis passing through the shielding space and in which the refractive index increases gradually from the two points in a direction opposite to the high refractive index region on the virtual optical axes, on which the two points are placed, so as to be close to the average refractive index.

A method and apparatus for authenticating a radar return signal include: generating an outgoing radar beam; generating a pair of entangled photons comprising a signal photon and an idler photon; combining the signal photon with the outgoing radar beam to generate a combined beam; sending the combined beam towards a target; receiving a return beam; detecting the signal photon from the return beam by a quantum illumination receiver; and making a joint detection with the idler photon.

A method and apparatus for authenticating a radar return signal include: generating an outgoing radar beam; generating a pair of entangled photons comprising a signal photon and an idler photon; combining the signal photon with the outgoing radar beam to generate a combined beam; sending the combined beam towards a target; receiving a return beam; detecting the signal photon from the return beam by a quantum illumination receiver; and making a joint detection with the idler photon.